ELECTRIC-RESISTANCE-WELDED STEEL PIPE WITH EXCELLENT TORSION FATIGUE RESISTANCE AND PROCESS FOR PRODUCING SAME

摘要

Conventional electric resistance welded steel pipes cannot always ensure fatigue resistance required as drive shafts. In detail, a base material portion of an electric resistance welded steel pipe has a composition including C at 0.25 to 0.55%, Si at 0.01 to 1.0%, Mn at 0.2 to 3.0%, Al at not more than 0.1% and N at 0.0010 to 0.0100%, with the balance being represented by Fe and inevitable impurities, and the weld defect area, which is a projected area of a weld defect in an electric resistance weld zone, is less than 40000 µm 2 .